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igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU 

This is a follow up of commit 915d975b2f ("net: deal with integer
overflows in kmalloc_reserve()") based on David Laight feedback.

Back in 2010, I failed to realize malicious users could set dev->mtu
to arbitrary values. This mtu has been since limited to 0x7fffffff but
regardless of how big dev->mtu is, it makes no sense for igmpv3_newpack()
to allocate more than IP_MAX_MTU and risk various skb fields overflows.

Fixes: 57e1ab6ead ("igmp: refine skb allocations")
Link: https://lore.kernel.org/netdev/d273628df80f45428e739274ab9ecb72@AcuMS.aculab.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: David Laight <David.Laight@ACULAB.COM>
Cc: Kyle Zeng <zengyhkyle@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2023-09-05 04:23:38 +00:00 committed by David S. Miller
parent d3287e4038
commit c3b704d4a4
1 changed files with 2 additions and 1 deletions
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3
net/ipv4/igmp.c
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@ -353,8 +353,9 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu)
struct flowi4 fl4;
int hlen = LL_RESERVED_SPACE(dev);
int tlen = dev->needed_tailroom;
unsigned int size = mtu;
unsigned int size;
size = min(mtu, IP_MAX_MTU);
while (1) {
skb = alloc_skb(size + hlen + tlen,
GFP_ATOMIC | __GFP_NOWARN);